Alternator & ChargingOwner reportCommunity Starter

2017 Porsche 911 — battery dies after the car sits for a weekend

HighwayTraveler957Community StarterMar 16, 20262017 Porsche 911 Carrera SLas Vegas

2017 Porsche 911 Carrera S, about 65,000 miles. Battery passes a quick test and charging voltage looks normal, but after two or three days parked the car sometimes will not crank. What is the cleanest parasitic-draw test on a modern car that takes time to go to sleep?

1 replies

NoMarkupLearner282Community StarterCommunity StarterMar 16, 2026permalink

Low-voltage gremlins will strand you even with a full pack. Try a second charger before blaming the 2017 Porsche 911 — site sharing and pack temp change the curve a lot. I'd do that before spending real money. This is from a 2017 Porsche 911 in Las Vegas with 65,000 miles. Time, temperature, and whether it's in gear are the notes that actually help a shop. No warning lights, which is why I'm documenting it.

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